EP1524430A2 - Starter-generator with automatically reverting freewheel - Google Patents

Abstract

Starter generator comprises a pulley, a shaft arranged within the pulley, and a free-wheel having a clamping body loaded with a spring arrangement. The free-wheel is formed as a double free-wheel and has clamping bodies (49, 51) with a spring unit (53) between them. The clamping bodies interact with clamping gaps. A hub (19) surrounds the shaft and the clamping bodies are arranged between the hub and the pulley. A spring coupling with springs (37, 39) is provided between the hub and the shaft. An independent claim is also included for a pulley for a starter generator. Preferred Features: The springs of the spring coupling have different strengths. The first spring (37) provides a relative movement between the hub and the shaft and the second spring (39) provides a relative movement between the hub and the shaft in the opposing direction.

Description

The invention relates to a starter generator with pulley, within the pulley arranged shaft and a freewheel, the loaded by a spring device clamping body, with the features mentioned in the preamble of claim 1 as well a pulley with the mentioned in the preamble of claim 8 Features.

State of the art

Belt driven starter generators for internal combustion engines of generic type are known. They are a favored variant for a low-closing starter system, which is used in vehicles with Start-stop automatic is used, since by the occurring Ten times the number of starts of conventional single-track starters can not be used anymore. In WO 01/77520 A1 and WO 01/88369 A1 are devices for coupling a belt-driven Starter generator with an internal combustion engine disclosed. These have a planetary gear with a sun gear on, wherein the torque reversal switch active by Coupling elements takes place.

Pulleys with freewheel, shortly belt freewheel disks also described in the prior art. They have a freewheel ring and clamping body with a spring device. This in the State of the art described pulleys with freewheel can but not used for the belt-driven starter generator come when using the belt-driven starter generator in starter mode, ie as a motor for starting an internal combustion engine, the torque in the opposite direction to the Torque in generator mode, ie when the internal combustion engine is running, occurs.

Advantage of the invention

The starter generator according to the invention with the mentioned in claim 1 Features offers the advantage over that in generator mode the function of the known freewheel pulley is met and opposite torques in starter operation be transmitted. This is through the use of a double freewheel achieved in the belt-driven starter generator. The double freewheel has pairs of mutually associated clamp body, between where the spring device is arranged. The clamp body interact with different clamping gaps. It is one provided the hub surrounding the shaft, being between hub and Shaft provided a spring coupling with at least two springs is. The clamping body between hub and pulley are with a control cage coupled to the pulley.

It is preferably provided that the coupling of the control cage with the pulley is effected by means of friction elements. Through this coupling the changeover of the double freewheel takes place at torque reversal. The advantage of a coupling by means of friction elements is that that the coupling is not rigid, but is operatively connected. she is on the other side so rigid that during a movement of the pulley the control cage the same movement as the pulley performs. When the direction of the pulley turns, thus also rotates the direction of movement of the control cage around.

It is preferably provided that the springs of the spring coupling between Shaft and hub have different stiffnesses. Thereby an angle range is preceded, the only small Can transmit torques. As a result, a "loose", wherein the "lots" has a larger angle than a difference angle between pulley and shaft. This difference angle arises in particular at the start of the engine and results from the non-uniform rotational speed of Internal combustion engine and out of that, under its inertial mass uniform rotating, starter generator. This nonuniformity is only quite large at the beginning of the boot process decreases with increasing speed of the internal combustion engine.

In a preferred embodiment of the spring coupling between Hub and shaft, the springs are designed as coil springs. The advantage here is that despite a small space a large impact is reached.

In addition to the effect of the springs, in a further preferred Embodiment also damping rooms available be filled with at least one medium. These muffling rooms form between the driver of the wave and the Inner contour of the hub. They act like throttles. As a medium can have gases with different compressibility properties or liquids with different viscosities used become.

In a preferred embodiment, the clearance angle of the Federkopplung be set, namely by series connection of at least two hubs with drivers and associated Feathers. The geometric series connection of the hubs with drivers and associated springs can both on the axle the shaft one behind the other, so axially, take place, as well as coaxially. Coaxial here means annularly arranged around the shaft scars. In each case, the inner hub represents the shaft for the next Hub, making multiple hub and shaft pairs in between arranged springs are realized. It is possible the clearance angle by using different springs with different ones To increase stiffness

characters

FIG. 1:

Arrangement of the belt driven according to the invention Starter generator and an internal combustion engine,

FIG. 2:

Longitudinal section of the starter generator along the line I-I from Figure 1 at rest,

FIG. 3:

Longitudinal section of the starter generator along the line I-I from Figure 1 in starter mode,

FIG. 4:

Longitudinal section of the starter generator along the line I-I from Figure 1 in the generator mode.

Figure 1 shows an arrangement of a starter generator 1 with a Shaft 3, which has a shaft axis 4 and with the starter generator 1 is connected. The shaft 3 is part of a device 5, from the only one pulley 7 is shown in this figure. The pulley 7 is by means of a belt 9 with a pulley eleventh an internal combustion engine 15 is connected. The pulley 11 is connected by a shaft 13 to the engine 15.

FIG. 2 shows the starter generator 1 according to the invention with the device 5 along the line I-I of the arrangement shown in Figure 1 shown. Identical parts are designated by the same reference numerals. It Reference is made to the description of Figure 1 to repetitions to avoid.

The device 5 has the pulley 7, the shaft 3 of the starter generator 1 and one between the shaft 3 and the pulley 7 arranged hub 19. The shaft 3 has an outer Circumference 21 a driver 23, which integral with the Wave 3 is connected. The driver 23 has a nearly rectangular Base surface 25, the almost vertical side surfaces 26th and 26 '. In the figure, only the rectangular base 25 shown. A geometric dimension of the driver 23 in FIG Direction of the shaft axis 4 can not be seen in the sectional view. The hub 19 has an inner contour 29. On the inner contour 29 is integrally formed with the hub 19, a driver 31. Of the driver 31 is also a base 33 in the Figure shown. The base 33 of the hub 19 has a nearly perpendicular to the inner contour 29 of the hub 19 aligned side surfaces 35 and an almost parallel to this side surface 35 'on. Between the side surface 35 'of the driver 31 and the side surface 26 of the driver 23, a spring 37 is arranged. Between the side surface 26 'of the driver 23 and the side surface 35 of the Driver 33 is a spring 39 is arranged. The springs 37 and 39 have different stiffnesses. Rotates the shaft 3 dextrorotatory, the spring 39 is compressed, the turns Shaft 3 counterclockwise, the spring 37 is compressed. rotates However, when the hub 19 clockwise, the spring 37 is compressed and when the hub 19 is moved counterclockwise the spring 39 compressed. The shaft 3 and the hub 19 are So according to the springways 37 and 39 relative to each other rotatable. It can from the hub 19 to the shaft 3 torques be transferred and vice versa. By the different ones Stiffnesses of the springs 37 and 39 is the one for transmission the same torques necessary twist angle different large. The distance between the driver 23 and driver 31, the is adjustable by the springs 37 and 39, is referred to as clearance angle 41.

The hub 19 has an outer contour 43. Between the outer contour 43 of the hub 19 and the pulley 7 is a double freewheel 47 arranged. The double freewheel 47 has at least two Clamping elements 49 and 51 and a between two clamping elements 49 and 51 arranged spring means 53 and a control cage 55. In the present embodiment, the double freewheel six of the at least two clamping elements 49 and 51, So a total of twelve, each pairwise cooperating, Clamping elements. The control cage 55 is not shown here Friction elements with the pulley 7 operatively connected, so that a Torque is transmitted. This means that when turning the Pulley 7 in a direction of the control cage 55 in the same Direction is turned. Follows the load of the control cage 55th by the means of the hub 19 acted upon clamping elements 49th or 51, the control cage 55 is provided by means of friction elements Coupling with the pulley 7 prevented by the Hub 19 to be turned. The clamping elements 49 and 51 of Double Freewheel 47 can be used in different versions be, for example, as a roller clamp or balls.

It is also possible several hubs and shafts with springs in a row to switch. The series connection of hubs and Shafts can be axles and hubs connected axially one behind the other exhibit. It is also conceivable hubs and shafts coaxial, so onion-shaped, to switch one behind the other, with an internal one Hub serves as a shaft for the external hub.

Between the drivers of the hub 19 and the shaft 3 are Rooms are formed, which are preferably filled with media, the more or less compressible, and so to an additional Damping of bumps and noises. It is also conceivable that the springs are replaced by spaces that are filled with media be, so that the adjustment of the clearance angle by, for example two rooms filled with different compressible gases he follows. It is also possible that different sized throttles be formed through the rooms. Under media can be liquids or gases are understood. Generally speaking Liquids absorb opposing forces and thus a damping of Effect relative movement. The damping can be adjusted through the choice of the medium and the fact that the rooms with more or less large throttles interact by the respective Medium flows in and out.

Between the driver 23 of the shaft 3 and the driver 31 of the Hub 19, the clearance angle 41 is formed. It is, as already described, also possible to switch hubs and shafts one behind the other, so that the resulting clearance angle is the sum of the single clearance angle between each pair, consisting of a hub and a shaft, composed.

In Figure 3, the device 5 is shown in starter mode. A through the shaft 3 introduced right-handed torque, which is symbolized by the arrow 59, via the soft spring 39, which is shown here in block pressed state, from the driver 23 of the shaft 3 via the driver 31 of the hub 19 finally on the hub 19 transferred. Is the spring 39 as a soft spring, that is with low spring stiffness, be formed even at small Torques large shaft rotation angle and thus large difference angle generated to the hub 19. The hub 19 begins to turn and Thus, the control cage 55, the friction elements, not shown coupled to the pulley 7, through the pulley 7 withheld. Thus, a clamping gap 63 is released and the clamping body 49 transmits the clockwise torque, shown as arrow 59, from the hub 19 to the pulley 7. The clamp body 51 now form a self-lifting Freewheel. That is, the clamping body 51, by the centrifugal force the inner wall of the pulley 7 are pressed, run with the Pulley 7 as a rigid body, do not transmit moments and perform no relative movement to the pulley 7. rotates due to the nonuniformity of the internal combustion engine 15th the torque direction is around, so is due to the with clamping body 49 closed freewheel, the hub 19 accelerated by the spring 39. A reversal of the clockwise torque, the is transmitted via the spring 39 to the hub 19, takes place only when the spring travel of the spring 39 is fully utilized. If the two Mitnehmer 31 and 23 on the spring 37 collide, opens the over the clamping body 49 formed freewheel 41. The over the Clamping 51 formed freewheel 41 can now close. It would be at this time torques from the pulley 7 via the hub 19 has been transferred to the shaft 3, causing damage would have led to the shaft 3, if the reversal of the freewheel of Clamping would not have occurred. Therefore, the clearance angle 41 between the driver 23 and the driver 31 is selected be that before closing the clamp body 51 of the Torque input caused by the reversal of the direction of torque was caused, must be finished. Is particularly advantageous it, if one of the spring 39 and the clearance angle 41 compensatable angular difference, which is greater than / equal to the largest Differential angle during startup is.

The clearance angle 41 and thus the compensatable angular difference can be enlarged by hubs with drivers and springs in a row be switched. Under series connection can both an axial series of hubs and shafts be understood, as well as a coaxial series connection analogous to a onion-like structure. In the coaxial series connection of hubs and shafts each acts the outside a hub as a shaft for the next overlying hub.

In FIG. 4, the device 5 is in generator operation, that is, while it is running Internal combustion engine 15 shown. A right-handed torque, shown as arrow 65, the pulley moves 7th dextrorotatory and drags by means of the friction elements, not shown the control cage 55 clockwise with. This will be Clamping column 61 released for the clamping elements 51. The clamping elements 51 are moved by the springs 53 in clamping gaps 61 and thus transmit the dextrorotatory torques 65 from the Pulley 7 on the hub 19. The driver 31 transmits the spring 37 the right-handed torque on the driver 23 on the shaft 3. The clamping body 49 are through the control cage 55 prevented from falling into the nip 63 and become pressed by the centrifugal force to the outside, so they with the pulley 7 rotate as a rigid body, so no torque transfer. They form such a low-wear self-lifting Freewheel.

Before starting the engine 15, it is necessary despite Using a belt tensioner in the side of the belt 9, the between Pulley 7 and pulley 11 is the belt tension in the area of the belt 9 between the pulley 7 of the starter generator 1 and the pulley 11 of Internal combustion engine 15 is to put under load. For this purpose, the Pulley 7 of the starter generator 1 counterclockwise turned in the left direction. Since the pulley 11 of Internal combustion engine 15 is at rest, the belt 9 spans between Pulley 7 of the starter generator 1 and pulley 11 of the internal combustion engine 15. In the device 5, the in Figure 4 described ratios for the clamping body 49 and 51 on. The shaft 3 rotates counterclockwise and the Driver 23 is moved to the driver 31 of the hub 19 out and thus transmits the left-handed torque 69 to the hub 19. By the rotation of the hub 19 in the counterclockwise direction the clamping body 51 is moved to the clamping body 49 to. Because the Pulley 7 is not in motion remain the control cages 55th at rest and it is the clamping gap 61 is released. The springs 53 Press the clamp body 49 lying in front of the springs 53 in the Clamping column 63 and thus transmit the torque 69 of the Hub 19 on the pulley 7. The pulley 7 is thus rotated and tensioned the belt 9 between the pulley 7 of the Starter generator 1 and pulley 11 of the internal combustion engine 15 against the negative drag torque of the internal combustion engine 15, since the pulley 11 is at rest.

As a result, a better wedging of the belt 9 to a during the starting process of the internal combustion engine 15 load-facing Angular range of the pulley 11 of the internal combustion engine reached. Ultimately, such a higher initial Transfer starting torque, without causing slippage of the Belt 9 is coming.

It is also conceivable, the pulley 7 additionally only on To provide internal combustion engine 15.

Claims (8)

Starter generator with a pulley, arranged within the pulley shaft and a freewheel which has a loaded by a spring device clamping body, characterized in that the freewheel is designed as a double freewheel and pairwise mutually associated clamping body (49, 51), between which the spring means (53) is arranged, which cooperate with different clamping gaps (61, 63) that at least one hub (19) surrounding the shaft (3) is provided, that the clamping body (49, 51) between hub (19) and pulley (7 ) are arranged with a with the pulley (7) coupled to the control cage (55), and that between the hub (19) and shaft (3) has a spring coupling with at least two springs (37, 39) is provided. Starter generator according to claim 1, characterized in that the coupling between the control cage (55) and pulley (7) takes place by means of at least one friction element. Starter generator according to claim 1 and 2, characterized in that the at least two springs (37, 39) of the spring coupling have different stiffness, wherein at least one first spring (37) during a relative movement between the hub (19) and shaft (3) and at least one second spring (39), acts in a relative movement between the hub (19) and shaft (3) in the opposite direction. Starter generator according to one of the preceding claims, characterized in that the springs (37, 39) are designed as spiral springs. Starter generator according to one of the preceding claims, characterized in that between the drivers (23, 31) with at least one medium filled damping chambers are present. Starter generator according to one of the preceding claims, characterized in that a clearance angle (41) between the driver (23) of the shaft (3) and the driver (31) of the hub (19) by the stiffness of the springs (37, 39) of the spring coupling be determined. Starter generator according to one of the preceding claims, characterized in that the clearance angle (41) by connecting in series of at least two hubs (19) with driver (31) and associated springs (37, 39) is adjustable. Pulley, in particular for a starter generator, according to one of claims 1 to 7, arranged with a pulley shaft and a freewheel having a loaded by a spring device clamping body, characterized in that the freewheel is designed as a double freewheel and pairwise associated clamping body (49, 51), between which the spring device (53) is arranged, which cooperate with different clamping gaps (61, 63), that at least one hub (19) surrounding the shaft (3) is provided, that the clamping bodies (49, 51) between the hub (19) and pulley (7) with a with the pulley (7) coupled to the control cage (55) are arranged, and that between the hub (19) and shaft (3) has a spring coupling with at least two springs (37, 39 ) is provided.

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